Lu Jianli, Deutsch Carol
Department of Physiology, University of Pennsylvania, PA 19104, USA.
Department of Physiology, University of Pennsylvania, PA 19104, USA.
J Mol Biol. 2014 Dec 12;426(24):4061-4073. doi: 10.1016/j.jmb.2014.10.006. Epub 2014 Oct 13.
All proteins, from bacteria to man, are made in the ribosome and are elongated, one residue at a time, at the peptidyl transferase center. This growing peptide chain wends its way through the ribosomal tunnel to the exit port, ~100Å from the peptidyl transferase center. We have identified locations in the tunnel that sense and respond to single side chains of the nascent peptide to induce local conformational changes. Moreover, side-chain sterics and rearrangements deep in the tunnel influence the disposition of residues 45Å away at the exit port and are consistent with side-chain-induced axial retraction of the peptide backbone. These coupled responses are neither haphazard nor uniform along the tunnel. Rather, they are confined to discriminating zones in the tunnel and are sequence specific. Such discerning communication may contribute to folding events and mechanisms governing sequence-specific signaling between different regions of the tunnel during translation.
从细菌到人类，所有蛋白质都是在核糖体中合成的，并在肽基转移酶中心一次延伸一个残基。这条不断增长的肽链蜿蜒穿过核糖体通道，到达距离肽基转移酶中心约100埃的出口。我们已经确定了通道中能够感知新生肽的单个侧链并做出反应以诱导局部构象变化的位置。此外，通道深处的侧链空间效应和重排会影响距离出口45埃处残基的排列，这与侧链诱导的肽主链轴向收缩一致。这些耦合反应在通道中既不是随机的也不是均匀的。相反，它们局限于通道中的辨别区域，并且具有序列特异性。这种有识别能力的通讯可能有助于折叠事件以及在翻译过程中控制通道不同区域之间序列特异性信号传导的机制。
